It’s never easy for candidates to separate themselves from politicians they once served.

Hillary Clinton will try to walk that tightrope if she runs for president, signaling where she disagreed with President Barack Obama’s foreign policy moves without sounding disloyal to the man who made her secretary of state.

Mrs. Clinton is about to come out with a new book, “Hard Choices,” that will offer clues as to how she would distinguish herself from her old boss. But it’s already clear she’ll run as more of a hawk: less hesitant to use military force and more willing to get involved in messy overseas conflicts.

That memo could prove useful to Mrs. Clinton on the campaign trail. Don’t be surprised if she mentions it in her book. It supports the idea that she was a clear-eyed realist when it came to Russian President Vladimir Putin, as opposed to some other White House officials who weren’t yet ready to abandon the reset policy.

“Was Secretary Clinton eyes wide open about Putin? Yes, absolutely,” said Michael McFaul, former U.S. ambassador to Russia.

When it comes to foreign policy, veering to the right of Mr. Obama plays to Mrs. Clinton’s advantage. Sexism persists in American politics and a female presidential candidate must always overcome suspicions that she’s not tough enough to serve as commander in chief. Her campaign operatives worried about that when she ran in 2008, and so devised a strategy emphasizing what they repeatedly called her “strength.”

Keeping some distance from Mr. Obama may pay dividends in other respects. Mr. Obama has come under criticism for seeming to dither when it comes to using military force. Last year, he was on the brink of launching an attack against Syrian leader Bashar al-Assad over the use of chemical weapons in the long-running civil war in Syria, only to pull back in favor of a diplomatic solution.

The war in Syria continued apace, and just last week Mr. Obama pledged to ramp up support to the Syrian opposition.

Mrs. Clinton can make the case that she had called for a more robust U.S. response to the war at a much earlier stage. Behind the scenes, she had urged the White House to train and arm moderate rebels, but lost the internal bureaucratic battle.

One longtime adviser said Mrs. Clinton was seriously looking at the idea of arming the rebels as early as April 2012, when the two met at the State Department and Mrs. Clinton appeared to be soliciting “additional arguments for why this was the right thing to do.”

Can Mrs. Clinton persuade Americans that she was on the right side of the Syria issue and the Russian reset without showing up Mr. Obama? Watch for how she navigates these difficult waters in her upcoming book tour.

About Washington Wire

Washington Wire is one of the oldest standing features in American journalism. Since the Wire launched on Sept. 20, 1940, the Journal has offered readers an informal look at the capital. Now online, the Wire provides a succession of glimpses at what’s happening behind hot stories and warnings of what to watch for in the days ahead. The Wire is led by Reid J. Epstein, with contributions from the rest of the bureau. Washington Wire now also includes Think Tank, our home for outside analysis from policy and political thinkers.